I could not seem to find any information on the parameters available in normal YouTube links. However, since we can't embed a video with extra parameters anyway, by using a different link format that goes to https://www.youtube.com we can use the embedded player parameters. As an example I am going to use the related, start, end, autoplay, autohide controls, and display fullscreen button parameters in a link:

It will only work with https links in that format, it won't work as intended if the link is a regular http address. As luck would have it, DU3 seems to not like https links unless they are in a [link] tag. So this whole thing is perhaps more effort than it is worth - but it may come in handy for a long video where only the relevant portion could be shown by specifying start and end points.

Adding a different link format that works better with the HTML5 player. Same parameters as above just using the embed format to unsecure YouTube site: